Tuesday, April 22, 2014

Human Embryos Cloned, Killed to Harvest Stem Cells

In a similar manner that Dolly the sheep was cloned in 1996 (somatic cell nuclear transfer, or SCNT), researchers implanted DNA from two men into four women's eggs and then "created" living human beings, which they destroyed in order to produce stem cell lines for further research.

“This and every technical advance in cloning human tissue raises the possibility that somebody will use it to clone a human being, and that is a prospect everyone is against.”-- Marcy Darnovsky, Executive Director, Center for Genetics and Society (Berkeley, CA)

The first success in humans was reported last year by scientists at the Oregon Health & Science University and the Oregon National Primate Research Center. But they used donor cells from infants. In this study, the cells came from two men, a 35-year-old and a 75-year-old.

While the research published Thursday involves cells that are technically an early stage embryo, the intention is not to try to grow them into a fully formed human. However the techniques in theory could be a first step toward creating a baby with the same genetic makeup as a donor.

The research was conducted in California by a large team that included representatives from both academia and industry and was funded by a private medical foundation and South Korea’s Ministry of Science.

At least 15 states have laws addressing human cloning. About half of them ban both reproductive and therapeutic cloning.

The advance, described online in the journal Cell Stem Cell, is the first time researchers have achieved "therapeutic cloning" of adults. Technically called somatic-cell nuclear transfer, therapeutic cloning means producing embryonic cells genetically identical to a donor, usually for the purpose of using those cells to treat disease.

But nuclear transfer is also the first step in reproductive cloning, or producing a genetic duplicate of someone . . .

If the embryo were implanted in a uterus, it could develop into a clone of the DNA donor, which is how Dolly was created. "Without regulations in place, such embryos could also be used for human reproductive cloning, although this would be unsafe and grossly unethical," said Dr Robert Lanza, chief scientist of Massachusetts-based biotech Advanced Cell Technology and a co-author of the new study.

The goal is to grow these embryonic stem cells in lab dishes and coax them to turn into specialized cells for therapeutic use against an illness the DNA donor has, such as Parkinson's disease, heart disease, multiple sclerosis or type-1 diabetes. Because the cells are genetically identical to the donor's, they would not be rejected by the immune system.

The scientists in Oregon and the authors of the new report acknowledged that the clones they created could develop into babies if implanted in surrogate wombs. But like others in the field, they have said reproductive cloning would be unethical and irresponsible.

Experts who were not involved in the experiments said the achievement was significant because it offered clear confirmation that so-called therapeutic cloning is possible with human cells. Given the field's history of fraudulent claims, such confirmation was valuable, said stem cell researcher Sean Morrison, director of the Children's Medical Center Research Institute at UT Southwestern.

Dr Robert Lanza, the chief scientific officer for Advanced Cell Technology Inc., has been working on SCNT off and on for about 15 years.

In the years that Lanza spent working on therapeutic cloning, many of his colleagues shifted their focus to a method that uses viruses and other compounds to rewind a cell to an earlier, more flexible state of development. The researcher who first developed these induced pluripotent stem cells, or iPS cells, won a Nobel Prize for the work.

With so much momentum behind iPS cells, it's unlikely that the new study will prompt many researchers to return their focus to SCNT, said Dr Arnold Kriegstein, director of the Developmental and Stem Cell Biology Program at UCSF School of Medicine.

"With the iPS technology, almost any molecular biology lab can create stem cell lines using simply skin cells, or even blood cells," said Kriegstein, who wasn't involved in the cloning studies.